1. Field of the Invention
The invention relates to a vehicle shift control system that includes a parking lock device that changes rotation teeth, rotating integrally with a wheel, between a locked state and a non-locked state; and a lock indicator lamp that turns on to indicate the locked state and, more particularly, to a shift-by-wire technology for electrically changing the shift position of a vehicle on the basis of a request signal for changing the rotation teeth between the locked state and the non-locked state.
2. Description of the Related Art
There is widely known a vehicle shift control system. The vehicle shift control system includes a parking lock device and a lock indicator lamp. The parking lock device changes rotation teeth, rotating integrally with a wheel, between a locked state where a lock tooth engages the rotation teeth and a non-locked state where the locked state is released. The lock indicator lamp turns on to indicate the locked state. The vehicle shift control system employs a so-called shift-by-wire (SBW) system that activates the parking lock device on the basis of a request signal to change the rotation teeth between the locked state and the non-locked state. By so doing, a shift position for vehicle driving is electrically changed. For example, there is a vehicle shift control system that uses a sensor, or the like, to detect an operating position of a shift operating device, such as a lever position of a shift lever, operated by a driver, and then electrically controls changing the shift position of the vehicle into a shift position corresponding to the shift operation on the basis of a position signal that indicates the detected lever position. Specifically, when the shift position determined on the basis of the position signal from the sensor is a driving position, the vehicle shift control system outputs a control signal to the vehicle to place the vehicle in a vehicle driving state according to the driving position. In addition, when the determined shift position is a parking position (P position), the vehicle shift control system actuates parking lock for inhibiting the rotation of the drive wheels in such a manner that a control signal is output to a parking lock device that mechanically inhibits the rotation of drive wheels to activate the parking lock device. Then, when the parking lock is set, the vehicle shift control system turns on the lock indicator lamp for indicating the locked state to the driver. For example, Japanese Patent Application Publication No. 2002-254954 (JP-A-2002-254954) describes a vehicle transmission control system and a shift operating member. The shift operating member includes an operating portion and a base. The operating portion has a plurality of light-emitting portions. The base supports the operating portion having a plurality of position indicators that indicate respective connected states of a transmission at portions corresponding to the light-emitting portions. The vehicle transmission control system employs a shift-by-wire system that turns on the position indicator and light-emitting portion corresponding to a current connected state of the transmission.
Here, there is a case where parking lock is actuated by a factor other than user's shift operation for setting the locked state. For example, when there occurs an external factor for charging a battery with electric power supplied from an external power supply to a vehicle as described in Japanese Patent Application Publication No. 7-87607 (JP-A-7-87607), it may be necessary to not only perform plug-in charging during a stop of the vehicle but also perform plug-in charging in a state where parking lock is set.